Odontogenesis is the term for tooth development. This describes the process by which baby and permanent teeth form in the mouth. This is a multistage process that begins with the initiation stage, a prenatal stage. The most common developmental issues in this stage are hypodontia which is when a tooth fails to form. Typically the teeth that fail to form are the permanent third molars, the maxillary lateral incisors, and the mandibular second premolars. A second common developmental issue of this phase of tooth development is hyperdontia or extra teeth. The most common location for extra teeth are between the maxillary central incisors, distal to the third molars, or in the premolar region.
Next is the bud stage which occurs during the eighth week of pregnancy and results in the formation of ten “tooth” buds in the upper and lower jaw of the fetus. Developmental anomalies that occur in this stage are related to the size of one, multiple, or all of the teeth. These conditions are called microdontia or smaller that normal tooth size, versus macrodontia which is larger than normal tooth size.
The third stage of tooth development is the cap stage and it occurs between the ninth and tenth week of pregnancy. The defects that can occur in this stage typically involve enamel formation. Dens in dente or tooth within a tooth which appears as an extremely deep pit on a fully erupted tooth. It usually affects the permanent maxillary lateral incisor. Germination, when a single tooth tries unsuccessfully to divide into two teeth, or fusion, when two separate teeth try to join together can also happen during this stage. Both of these defects are likely to occur in the front teeth.